1. Field of the Invention
The present invention relates to stabilized polymeric compositions, and more particularly relates to polyolefin particles coated with a phosphite stabilizer.
2. Description of the Related Art
Coating of polyolefin beads with phosphorous stabilizer compounds is known, and such processes have general involved melting of a solid phosphonite (phosphorous compound) stabilizer and spray coating polyolefin beads. Polyolefin beads may be made by any of conventional processes such as the Spheripol and Spherdene processes. Typical bead formation processes involve formation of polymer about catalytic seed particles to grow uniform shaped polyolefin beads. The above mentioned prior coating processes have typically had one or more of the following disadvantages: (1) requiring a melting step above 120.degree. C. to place the high melting temperature phosphorous compounds in suitable condition for spray coating onto the beads, and (2) having a low hydrocarbon solubility (typically high molecular weight) resulting in coated polyolefin beads which exhibit an apparent morphology of a distinct polyolefin core and a distinct phosphonite compound shell surrounding the core without penetration of the compound into the outer surface of the core. Such shell configuration can result in undesirable levels of hydrolysis of the phosphorous compound upon extended exposure of the particles to humidity. And simple compounding processes undesirably expose the polymer and phosphorous compound to degradation upon exposure to heat and shear in the presence of oxygen.